Hi, first post here, problem with Worcester Boiler.

[minardifans]

Hi, I have a Worcester 24i RSF combi boiler. Now the problem I have with the boiler is that I believe the expansion vessel has failed.

I have tried replacing the PRV to no effect and now the pressure rises too much when the heating is on (up to 3bar) and drops to zero when the heating is off. I have tried pressing the valve on top of the expansion vessel and water does squirt out.

Now I have seen some very informative guides on here about replacing the vessel with an external one, which normally place the vessel on the return feed but I have a few questions...

1) There is a pipe that comes from the pump and up to the expansion vessel. Can I simply cut this pipe and re-plump it to an external vessel underneath the boiler or is it better to leave the old one in situ and plumb it into the return. I can access this pipe quite easily and it seems easier for me to just re-pipe it from the pump.

2) does it matter which way up the expansion vessel goes?


Many thanks.

Rob.

 

[Tom1981]

I'd call out a engineer it's very very unlikely you'll need a new vessel.

A vessel should be recharged frequently, some last a good few years, some only a year. I recharge allot in my normal working week.


It's more than likely the vessel needs recharging. It's lost it's charge pressure, water needs something less dense to push against, there's a bladder of air inside. This has to be recharged to the correct pressure. If there's water squirting out of the Schrader valve this is most likely condensation, the rubber inside a vessel very strong and thick and doesn't split as much as some people think.

You can't just cut a vessel out of a boiler, you can repipe a external vessel close to the appliance on the return pipe work and leave the damaged vessel in place.

 

[boilerdoktor]

your knowledge is so limited that i would probably get a professional, it may be beyond you. please don t take this the wrong way

 

[Tom1981]

Also, DIY work on a Gas boiler is not advisable

 

[minardifans]

I'd call out a engineer it's very very unlikely you'll need a new vessel.

A vessel should be recharged frequently, some last a good few years, some only a year. I recharge allot in my normal working week.


It's more than likely the vessel needs recharging. It's lost it's charge pressure, water needs something less dense to push against, there's a bladder of air inside. This has to be recharged to the correct pressure. If there's water squirting out of the Schrader valve this is most likely condensation, the rubber inside a vessel very strong and thick and doesn't split as much as some people think.

You can't just cut a vessel out of a boiler, you can repipe a external vessel close to the appliance on the return pipe work and leave the damaged vessel in place.

It is a very old boiler... 1994 I think. I will try recharging it first following the guide and go from there.

 

[minardifans]

your knowledge is so limited that i would probably get a professional, it may be beyond you. please don t take this the wrong way

I am a very competent person.

 

[Tom1981]

I'd call out a engineer it's very very unlikely you'll need a new vessel.

A vessel should be recharged frequently, some last a good few years, some only a year. I recharge allot in my normal working week.


It's more than likely the vessel needs recharging. It's lost it's charge pressure, water needs something less dense to push against, there's a bladder of air inside. This has to be recharged to the correct pressure. If there's water squirting out of the Schrader valve this is most likely condensation, the rubber inside a vessel very strong and thick and doesn't split as much as some people think.

You can't just cut a vessel out of a boiler, you can repipe a external vessel close to the appliance on the return pipe work and leave the damaged vessel in place.

It is a very old boiler... 1994 I think. I will try recharging it first following the guide and go from there.

I wouldn't use a guide. 1994 maybe old, but I work on much older

You need to drain the condensation first' does the guide mention that or the correct pressure to charge the vessel too and how to do it?

If its over charged you'll get the same problem, uncharged it'll keep dumping pressure.

 

[minardifans]

I'd call out a engineer it's very very unlikely you'll need a new vessel.

A vessel should be recharged frequently, some last a good few years, some only a year. I recharge allot in my normal working week.


It's more than likely the vessel needs recharging. It's lost it's charge pressure, water needs something less dense to push against, there's a bladder of air inside. This has to be recharged to the correct pressure. If there's water squirting out of the Schrader valve this is most likely condensation, the rubber inside a vessel very strong and thick and doesn't split as much as some people think.

You can't just cut a vessel out of a boiler, you can repipe a external vessel close to the appliance on the return pipe work and leave the damaged vessel in place.

It is a very old boiler... 1994 I think. I will try recharging it first following the guide and go from there.

I wouldn't use a guide. 1994 maybe old, but I work on much older

You need to drain the condensation first' does the guide mention that or the correct pressure to charge the vessel too and how to do it?

If its over charged you'll get the same problem, uncharged it'll keep dumping pressure.

Well the guide is one from here, so yes it explains it all apart from draining the condensation. The guide for this model says 0.5 bar for the expansion vessel.

 

[mcmoby69]

I am a very competent person

have you read your own first post ???????

how does changing a prv fix an expansion vessel problem?

 

[minardifans]

I am a very competent person

have you read your own first post ???????

how does changing a prv fix an expansion vessel problem?

We replaced the PRV because that was also faulty. It was always dripping even when the pressure was very low. That's why it was replaced. It now doesn't drip when the pressure is low. So I diagnosed that problem and solved it. Don't really know what you think I did wrong there?
We didn't know we had an expansion vessel problem until the faulty old PRV was replaced. The boiler was always loosing pressure i.e. dripping out of the pipe outside. When the heating was on this would simply get worse and pressure would drop to zero. There expansion vessel was therefore never doing any work because the PRV was always dumping the pressure out of the system. Now that it's been replaced (the PRV) the pressure is rising too high when the CH is on.

 

[mcmoby69]

prv activates when the pressure gets too high. usually indicated by the pressure guage.
once its activated it sometimes doesnt seal properly even at low pressure causing a drip. usually due to crap in the system from constant topping up

so replacing the prv wont fix it. the prv activated for a reason not just for fun.

prv opened because the expansion vessel was either low on pressure or has failed.

 

[minardifans]

prv activates when the pressure gets too high. usually indicated by the pressure guage.
once its activated it sometimes doesnt seal properly even at low pressure causing a drip. usually due to crap in the system from constant topping up

so replacing the prv wont fix it. the prv activated for a reason not just for fun.

prv opened because the expansion vessel was either low on pressure or has failed.

I know the PRV won't fix it alone. But I also knew that the PRV had failed, i.e. wouldn't shut because of the constant drip and loss of pressure even when the CH was not on. I replaced the PRV because the system was losing pressure constantly. I can see now that the system will hold pressure that there is a problem with the Expansion Vessel. This didn't show before because of the PRV constantly dumping the pressure down the drain. There was no point doing anything with the Expansion vessel when the PRV was stuck open.

The evidence that lead me to believe that the Expansion vessel had failed was water from the top when pressing the valve, although the poster above believes this could be condensation. So if you have a good method of removing this condensation from the top of the Expansion vessel before I follow the guide of re-charging it with air I would be very grateful.

 

[Tom1981]

To drain the condensation you need to remove the core of the Schrader valve, attach a small hose or rubber pipe over the now open valve. Next fill the system to around 2.5bar, this will force out the condensation, do this until condensation stops running from the vessel. Now dump any pressure from the system and leave the drain valve open, refit the core and using a foot pump recharge the vessel, Worcesters tend to be .7bar. You'll notice water will drain from the open drain point whilst your charging the vessel. Once you've pumped up the pressure, close the drain point and refill the system to 1bar and vent the air, repressurise if needed.

 

[Agile]

I can see now that the system will hold pressure that there is a problem with the Expansion Vessel. This didn't show before because of the PRV constantly dumping the pressure down the drain. There was no point doing anything with the Expansion vessel when the PRV was stuck open.

We did tell you several times!

Before recharging the EXV you should let ALL the presssure out whilst the system is still pressurised.

Put 0.9 bar of air in with the system OPEN to the atmosphere.

Then recharge to about 1.5 Bar.

Its easy really if you follow our instructions! Of course if you are more competent then it may take you a little longer.

Tony

 

[minardifans]

I can see now that the system will hold pressure that there is a problem with the Expansion Vessel. This didn't show before because of the PRV constantly dumping the pressure down the drain. There was no point doing anything with the Expansion vessel when the PRV was stuck open.

We did tell you several times!

Before recharging the EXV you should let ALL the presssure out whilst the system is still pressurised.

Put 0.9 bar of air in with the system OPEN to the atmosphere.

Then recharge to about 1.5 Bar.

Its easy really if you follow our instructions! Of course if you are more competent then it may take you a little longer.

Tony

I don't understand at what point you've told me something several times.

I haven't attempted to recharge the EXV yet. I haven't touched the EXV since changing the PRV. Only to press the valve in to see if either air or water comes out the top. Water came out so this could either be Condensation or a EXV failure. I have asked for advise to eliminate if it is condensation before taking further steps. Surely this is the correct course of action.